The present invention relates to a composite sliding structure suitable for bearing portions or sliding portions of automobiles, ships, various kinds of electric machines, office automation equipments, agricultural machines, machine tools, food processing apparatus, and any other industrial machines.
There has been provided such a composite sliding structure composed of three layers, that is, a surface layer, an intermediate layer and a backing layer, For example, the surface layer is made of Pb-base alloy containing Sn of 4% or more, the intermediate layer being made of Cu-base alloy, and the backing layer is made of steel. Also, there has been provided a four layer structure of a surface layer, a bond layer, an intermediate layer and a backing layer. For instance, the surface layer is made of Pb base alloy containing Sn of 4% or more, the bond layer being made of Ni or Ni-alloy, the intermediate layer being made of Al base alloy, and the backing layer is made of steel. Alternatively, there has been a four layer composite sliding structure that contains 4% or more Sn in either of the surface layer and the intermediate layer.
In a case of bearing of an internal combustion engine, a bearing used at a high temperature or the like, Sn of the Pb-base alloy surface layer would be diffused into the intermediate layer of Cu-base bearing alloy, or into the bond layer of Cu or Cu-alloy, or into the bond layer of Ni or Ni-alloy, thereby forming a brittle intermetallic compound of Cu-Sn or Sn-Ni, resulting in reduction in fatigue strength. Also, Sn in the intermediate layer of Al base alloy would be diffused into the Cu or Cu alloy bond layer, thereby forming a brittle Sn-Cu intermetallic compound, resulting in reduction in fatigue strength of the sliding structure.